Powdery/granular material flowability evaluation apparatus and method

ABSTRACT

A powdery/granular material flowability evaluation apparatus and a powdery/granular material flowability evaluation method are provided to evaluate the flowability of a powdery/granular material in a dynamic state of the powdery/granular material. The powdery/granular material flowability evaluation apparatus (A) has a hopper ( 111 ) for storing a powdery/granular material to be measured, a vertical tube ( 11 ) having a flow-in port ( 1121 ) connected with a discharge port ( 1112 ) of the hopper ( 111 ) through which the powdery/granular material is discharged, a vibrator ( 2 ) for giving vibration to the tube ( 11 ), a laser vibrometer ( 3 ) for measuring the amplitude of the tube ( 11 ), an electric balance ( 4 ) for measuring the weight of the powdery/granular material fallen through the tube  11  from the hopper ( 111 ), and an evaluation value calculating section ( 512 ) for calculating an evaluation value evaluating the flowability of the powdery/granular material based on the measured amplitude and weight.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/918,901 filed on Oct. 19, 2007.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to powdery/granular material flowabilityevaluation apparatus and method capable of relatively evaluatingpowdery/granular material flowability.

2. Description of the Related Art

Powdery/granular material flowability is evaluated, for example, bymeasuring an angle of repose, a degree of compaction or a degree ofaggregation. For example, an index value used to evaluate flowability iscalculated by the Carr method and evaluated.

A method for measuring an angle of repose, which method is utilized uponevaluating such flowability, is disclosed, for example, in JapaneseUnexamined Patent Publication No. 2002-162329. Japanese UnexaminedPatent Publication No. 2002-162329 discloses a method for measuring anangle of repose of a wet powdery/granular material using an apparatusincluding, from the top, a mesh screen, vibrating means for vibratingthe mesh screen, a powdery/granular material sample pouring funnel, atable used to measure the angle of repose, and a support for supportingthe vibrating means and the sample pouring funnel and particularly amethod for measuring an angle of repose of a wet powdery/granularmaterial, wherein the liquid content of the powdery/granular materialsample lies within a range of 10 to 60 weight %, the mesh size of thescreen mesh is 710 to 5600 and the diameter of the bottom orifice of thesample pouring funnel lies within a range of 5 to 15 mm.

Further, the Japanese Industrial Standards JIS Z 2502 (2000) or ISO 4490specifies a “Metallic Powdery/Granular Material—Flowability TestingMethod”. This “Metallic Powdery/Granular Material—Flowability TestingMethod” is roughly a method for measuring a time required for 50 g of ametallic powdery/granular material to flow through an orifice of acalibrated funnel (Hall flowmeter) of a standard size by means of a stopwatch and measuring the flowability of the metallic powdery/granularmaterial based on this time.

The evaluation method according to the background art is for evaluatingthe flowability of the powdery/granular material from the angle ofrepose, degree of compaction and degree of aggregation that are measuredin a stationary state of the powdery/granular material, but not formeasuring the flowability of the powdery/granular material in a dynamicstate of the powdery/granular material. Thus, evaluations by theevaluation method according to the background art could not be said toprecisely reflect the flowability of the powdery/granular material insome cases.

Further, since a test is conducted as described above according to the“Metallic Powdery/Granular Material—Flowability Testing Method”, thereis an inconvenience that the powdery/granular material to be measured islimited to a metallic powdery/granular material naturally discharged bythe action of gravity. The above “Metallic Powdery/GranularMaterial—Flowability Testing Method” cannot be applied, particularly, toadhesive powdery/granular materials.

SUMMARY OF THE INVENTION

In view of the above situation, an object of the present invention is toprovide powdery/granular material flowability evaluation apparatus andmethod capable of evaluating the flowability of a powdery/granularmaterial in a dynamic state where the powdery/granular material itselfis flowing or is about to start flowing.

The present inventors found out as a result of various studies that astarting point of the flow and a flow rate per unit time of apowdery/granular material flowing in a vibrating tube change dependingon the amplitude of the tube.

A powdery/granular material flowability evaluation apparatus accordingto one aspect of the present invention gives vibration to anaccommodating member accommodating a powdery/granular material andcalculates an evaluation value evaluating the flowability of thepowdery/granular material based on the amplitude of the given vibrationand the weight of the powdery/granular material having come out of theaccommodating member by giving the vibration. According to apowdery/granular material flowability evaluation method according toanother aspect of the present invention, vibration is first given to anaccommodating member accommodating a powdery/granular material andsubsequently an evaluation value evaluating the flowability of thepowdery/granular material is calculated based on the amplitude of thegiven vibration and the weight of the powdery/granular material havingcome out of the accommodating member by the given vibration.

It should be noted that the amplitude is related by an equation:(amplitude)=(acceleration of vibration)/(2×π×(frequency))². Theamplitude is proportional to the acceleration of the vibration if thefrequency is constant.

The powdery/granular material flowability evaluation apparatus andpowdery/granular material flowability evaluation method having such aconstruction can evaluate the flowability of the powdery/granularmaterial in a dynamic state where the powdery/granular material itselfis flowing or is about to start flowing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the construction of a powdery/granularmaterial flowability evaluation apparatus according to one embodiment,

FIG. 2 is a graph showing a frequency characteristic of a tube,

FIG. 3 are graphs showing a flow rate per unit time in relation toamplitude,

FIG. 4 is a graph showing the flow rate per unit time in relation toamplitude by continuous measurements,

FIG. 5 are views showing CT scan images obtained by photographing thestate of a powdery/granular material in the center of a narrower tubeportion,

FIG. 6 are graphs showing changes of the flow rate per unit time of thepowdery/granular material with time in the case of specified amplitudes,

FIG. 7 is a graph showing the flow rate per unit time in relation to thelapse of time,

FIG. 8 is a graph according to another example showing the cumulativeamounts of the powdery/granular material flowing out from the tube inrelation to an amplitude change in the case where the amplitude ofvibration is increased to a specified level,

FIG. 9 is a graph showing cumulative amounts of the powdery/granularmaterial flowing out from the tube in relation to an amplitude change inthe case of decreasing the amplitude of the vibration after increasingit to a specified level,

FIG. 10 is a horizontal section along X-X of FIG. 1, and

FIG. 11 is a graph showing the flow rate per unit time in relation tothe lapse of time in the case where vibrations having differentwaveforms are given to the tube in two directions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, one embodiment of the present invention is described withreference to the drawings. It should be noted that constructionsidentified by the same reference numerals in the respective figures areidentical constructions and are not repeatedly described.

(Construction of the Embodiment)

FIG. 1 is a diagram showing the construction of a powdery/granularmaterial flowability evaluation apparatus according to the embodiment.The powdery/granular material flowability evaluation apparatus A is anapparatus for giving vibration to an accommodating member accommodatinga powdery/granular material and calculating an evaluation valueevaluating the flowability of the powdery/granular material based on theamplitude of the given vibration and the weight of the powdery/granularmaterial flown out from the accommodating member by this givenvibration, and is provided with a powdery/granular material flowing unit1, a vibrator 2, a laser vibrometer 3, an electric balance 4 and anarithmetic unit 5 as shown in FIG. 1.

The powdery/granular material flowing unit 1 includes a tube 11, ahorizontal rod 12 supporting the tube 11 vertically (in other words,substantially in parallel with a direction G in which gravity acts), anda stand 13 for supporting the horizontal rod 12.

The tube 11 is an accommodating member for accommodating apowdery/granular material and comprised of a hopper part 111 for storingthe powdery/granular material to be evaluated and a tube part 112through which the powdery/granular material flows. The hopper part 111is formed at its upper end with a throw-in port 1111 to enable thepowdery/granular material to be poured thereinto, and is funnel-shapedto gradually reduce the diameter from the throw-in port 1111 to adischarge port 1112 so that the stored powdery/granular material cansmoothly flow to the discharge port 1112 to be discharged. The tube part112 has an flow-in port 1121 at the upper end connected with thedischarge port 1112 of the hopper part 111 and is formed with a narrowertube portion 1122 having a smaller inner diameter at the bottom end. Thetube 11 is supported on the horizontal rod 12 at the upper end of thetube part 112.

The inner diameter of the narrower tube portion 1122 is equivalent to adiameter at which the flowability of the powdery/granular material isdesired to be evaluated, and is suitably set according to the material,size, adhesiveness and the like of the powdery/granular material passingthe tube part 112. The outer diameter of the tube part 112 (i.e.thickness of the tube part 112) is suitably set to have such strengththat the tube 11 is not broken when vibration is given from the vibrator2 with the tube 11 supported on the horizontal rod 12. The length of thetube part 112 is not particularly limited as long as the vibration bythe vibrator 2 is transmitted to the entire tube 11, but is preferablyabout several hundreds mm in view of the miniaturization of theapparatus. The tube 11 is made of a material having such rigidity thatthe vibration by the vibrator 2 is transmitted to the entire tube 11,e.g. glass or metal (e.g. steel or copper).

Although the tube 11 is vertically arranged so that gravity maximallyacts on the powdery/granular material in this embodiment, it may beobliquely arranged at a specified angle to vertical direction since itis sufficient that gravity acts on the powdery/granular material.

The hopper part 111 is an example of a storage tank as claimed, and thetube part 112 is an example of a tube as claimed. In this embodiment,the storage tank and the tube as claimed are integrally formed asdescribed above.

The vibrator 2 is an apparatus for giving vibration to the tube 11 as anexample of the accommodating member at specified frequency and amplitudein accordance with a control signal from the arithmetic unit 5, andincludes a vibrator main body 21 for generating vibration and avibration transmitting member 22 for transmitting the vibrationgenerated in the vibrator main body 21. The vibrator main body 21 is,for example, an electromagnetic vibrator for vibrating a vibrating plateconnected to a movable coil disposed in a direct-current magnetic fieldproduced by a permanent magnet or an exciting coil by supplying analternating current to the movable coil; an electrostatic vibrator forvibrating a vibrating plate by forming a capacitor by a fixed electrodeplate and the vibrating plate and supplying a voltage, in which analternating-current voltage is superimposed on a direct-current biasvoltage, to the fixed electrode plate and the vibrating plate; anelectrostrictive vibrator for vibrating a vibrating plate by applying analternating-current voltage to an electrostrictive element that isdeformed upon the application of a voltage; or a vibration motor forgenerating vibration by rotating an eccentric weight attached to arotary shaft of the motor. For example, the vibrator main body 21 may bea piezoelectric acoustic vibrator including a piezoelectric element.Since the amplitude and frequency (number of vibration) of the vibrationcan be independently controlled in the piezoelectric acoustic vibrator,there is an advantage of easily continuously changing the amplitude withthe frequency fixed to a specified frequency set beforehand. Such apiezoelectric acoustic vibrator includes, for example, a donut-shapedpiezoelectric element having a pair of facing electrodes on the oppositesurfaces thereof and a metallic round piezoelectric vibrating plate,wherein the piezoelectric element is concentrically secured to onesurface of the piezoelectric vibrating plate. In the piezoelectricacoustic vibrator having such a construction, when voltages are appliedto the pair of facing electrodes, the piezoelectric vibrating plateneither elongates nor contracts while the piezoelectric elementelongates or contracts in a radial direction according to the polarityof the voltages, wherefore the piezoelectric vibrating plate is warpedupward or downward in a normal direction to the piezoelectric vibratingplate as the piezoelectric element elongates or contracts. Thus, theseupward and downward warps are alternately repeated by applying thealternating-current voltages to the pair of facing electrodes and thepiezoelectric vibrating plate vibrates. In this embodiment, anelectromagnetic vibrator or a piezoelectric acoustic vibrator is used asthe vibrator 2. The vibration transmitting member 22 is connected withthe bottom end of the tube part 112 at a side toward the narrower tubeportion 1122 to transmit vibration generated in the vibrator main body21 to the tube 11. It should be noted that the vibrator 2 may be anultrasonic vibration apparatus constructed to generate an ultrasonicwave and vibrate the tube 11 by irradiating this generated ultrasonicwave to the bottom end of the tube part 112. The vibrator 2 is anexample of a vibrator unit as claimed.

The laser vibrometer 3 is an apparatus for measuring the amplitude ofthe tube 11 and outputting the measured amplitude to the arithmetic unit5 and includes, for example, a laser vibrometer main body 31, a probe 32and an analog/digital converter (hereinafter, abbreviated as “A/D”) 33for converting an analog signal into a digital signal. The laservibrometer main body 31 causes the probe 32 to irradiate a laser beam tothe narrower tube portion 1122 in the vicinity of a flow-out port 1123and to receive the reflected light, calculates the amplitude by thelaser Doppler method based on a laser beam irradiation timing and alight receiving timing at specified sampling intervals (e.g. everysecond) set beforehand, and outputs the calculation result to thearithmetic unit 5 via the A/D 33. Since the vicinity of the flow-outport 1123 of the tube 11 where the powdery/granular material flows outis an open end of the vibration in this embodiment, the laser vibrometer3 is so arranged as to measure the amplitude of the narrower tubeportion 1122 in the vicinity of the flow-out port 1123 of the tube 11and output the measurement result to the arithmetic unit 5 in this way.The laser vibrometer 3 is an example of an amplitude meter as claimed.

The electric balance 4 is an apparatus for measuring the weight of thepowdery/granular material fallen through the tube part 112 from thehopper part 111 and outputting the measured weight to the arithmeticunit 5. In the electric balance 4, a weighing platform 41 on which anobject to be weight-measured is placed is disposed below the flow-outport 1123 of the tube 11. The electric balance 4 receives thepowdery/granular material falling from the tube part 11 with theweighing platform 41, measures the weight of the powdery/granularmaterial at the specified sampling intervals (e.g. every second) setbeforehand, and digitally outputs the measured weight to the arithmeticunit 5. The detection sensitivity of the electric balance 4 is suitablydetermined according to an average weight of one particle of thepowdery/granular material and accuracy required for the evaluation valueto be calculated, and is 0.1 mg in this embodiment. The electric balance4 is an example of a weight meter as claimed.

The arithmetic unit 5 is a unit for controlling the frequency andamplitude of the vibration generated by the vibrator 2 and calculatingthe evaluation value evaluating the flowability of the powdery/granularmaterial based on the amplitude measured by the laser vibrometer 3 andthe weight measured by the electric balance 4 in a dynamic state of thepowdery/granular material.

The arithmetic unit 5 includes, for example, a central processor 51, astorage device 52, an interface 53, an input device 54, an output device55 and a bus 56.

The interface 53 is an interface circuit for connecting the arithmeticunit 5 and an external apparatus in such a manner as to enable datainput and output therebetween. The interface 53 converts a controlsignal from the central processor 51 into a data of such a formatprocessable by the vibrator 2, and converts data from the laservibrometer 3 and electric balance 4 into data of such a formatprocessable by the central processor 51. The input device 54 is a devicefor inputting various commands such as a start command instructing thestart of the measurement of the evaluation value and various data suchas a value of the frequency of the vibration generated by the vibrator 2to the arithmetic unit 5 and is, for example, a keyboard, a mouse or thelike. The output device 55 is a device for outputting commands and datainputted from the input device 54, the evaluation value of thepowdery/granular material and the like and is, for example, a displaydevice such as a CRT display, an LCD, an organic EL display or a plasmadisplay or a printing device such as a printer.

The storage device 52 is for storing various programs such as a controlprogram for controlling the powdery/granular material flowabilityevaluation apparatus A and data generated during the execution of thevarious programs. The storage device 52 includes, for example, avolatile storage element such as a RAM (Random Access Memory) serving asa so-called working memory of the central processor 51 and nonvolatilestorage elements such as a ROM (Read Only Memory) and a rewritableEEPROM (Electrically Erasable Programmable Read Only Memory).

The central processor 51 includes, for example, a microprocessor, itsperipheral circuits and the like, is functionally provided with avibrator controlling section 511 for controlling the vibrator 2 togenerate the vibration of specified frequency and amplitude and anevaluation value calculating section 512 for calculating the evaluationvalue evaluating the flowability of the powdery/granular material basedon the amplitude measured by the laser vibrometer 3 and the weightmeasured by the electric balance 4, and controls the storage device 52,interface 53, input device 54 and output device 55 according to thesefunctions in accordance with the control program and further controlsthe vibrator 2 via the interface 53.

These central processor 51, storage device 52, interface 53, inputdevice 54 and output device 55 are connected by the bus 56 so as toexchange data to each other.

Such an arithmetic unit 5 can be, for example, constructed by acomputer, more specifically by a notebook or desktop personal computer.

The arithmetic unit 5 may further include an external storage device(not shown) according to needs. The external storage device is a devicefor reading and/or writing data in and from recording media such asflexible discs, CD-ROMs (Compact Disc Read Only Memories), CD-Rs(Compact Disc Recordables) or DVD-Rs (Digital Versatile DiscRecordables) and is, for example, a flexible disc drive, a CD-ROM drive,a CD-R drive, a DVD-R drive or the like.

Next, the operation of this embodiment is described.

(Operation of the Embodiment)

In the case of measuring an evaluation value on the flowability of apowdery/granular material, a measurer first determines a frequency(cycle) suited to measuring vibration given to the tube 11 by thevibrator 2. This is because the frequency characteristic of the tube 11connected with the vibrator 2 and supported by the horizontal rod 12differs depending on the powdery/granular material passing through thetube 11 to be measured. Thus, the frequency of the vibration given tothe tube 11 needs to be determined according to the powdery/granularmaterial to be measured.

Upon determining this frequency, the measurer starts the arithmetic unit5, the laser vibrometer 3 and the electric balance 4 and throws thepowdery/granular material to be measured into the hopper part 111 of thetube 11 through the throw-in port 1111, thereby preparing for ameasurement. Then, the measurer measures the amplitude of the tube 11while changing the frequency of the vibration given to the tube 11(frequency of the vibrator 2) within a specified range.

As examples, frequency characteristics of the tube 11 made of glass forpowdery/granular materials of polymethylmetacrylate, silicon oxide,aluminum oxide and copper having an average particle diameter of about10 μm are shown in FIG. 2. This glass tube 11 is such that the innerdiameter of the tube part 112 is about 6 mm, that of the narrower tubeportion 1122 at the bottom end of the tube part 112 is about 1.2 mm andthe entire length of the tube part 112 is about 150 mm with its bottomside of about 50 mm allotted as the narrower tube portion 1122. Further,the amplitude of the narrower tube portion 1122 in the vicinity of theflow-out port 1123 was measured as the amplitude of the tube 11.

FIG. 2 is a graph showing the frequency characteristics of the tube,wherein a horizontal axis represents frequency in Hz and a vertical axisrepresent amplitude in μm. ◯ represents measurement values in the casewhere the powdery/granular material was not passed through the tube 11.▪ represents measurement values in the case where PMMA(polymethylmetacrylate) was passed as the powdery/granular materialthrough the tube 11. ▴ measurement values in the case where SiO_(s)(silicon oxide) was passed as the powdery/granular material through thetube 11. ♦ measurement values in the case where Al₂O₃ (aluminum oxide)was passed as the powdery/granular material through the tube 11. measurement values in the case where Cu (copper) passed was as thepowdery/granular material through the tube 11.

As can be understood from FIG. 2, the respective frequencycharacteristics of the tube 11 differed in the case where thepowdery/granular material was passed through the tube 11 and in the casewhere no powdery/granular material was passed through the tube 11, andin the case where the material of the powdery/granular material waschanged. The respective frequency characteristics differ in this way,but have such a profile that a first order resonance appears at about330 Hz and higher order resonances appear before and after thisfrequency in the tube 11 having the above dimensions.

In the measurement of the evaluation value of the powdery/granularmaterial according to the present invention, the vibrator 2 needs to bedriven at least at a frequency at which the tube 11 vibrates since thetube 11 needs to be vibrated. The application of vibration to the tube11 at a resonance frequency is advantageous in view of powerconsumption, but is not preferable in view of measurement accuracy sincethe amplitude changes to a larger degree than a frequency change whenthe frequency changes. Therefore, in order to improve the measurementaccuracy, it is preferable to measure at a frequency at which theamplitude changes a little even if the frequency changes.

Since a frequency range of about 250 Hz to about 300 Hz is the onewithin which the amplitude changes a little even if the frequencychanges in the case of FIG. 2, a measurement frequency is preferablydetermined within this frequency range.

Further, in the case of measuring an evaluation value for one kind ofpowdery/granular material, it is sufficient to select a certainfrequency from the frequency range as described above. However, in thecase of measuring evaluation values for a plurality of kinds ofpowdery/granular materials without changing the measurement frequency,it is preferable to conduct measurements for the respectivepowdery/granular materials at such a frequency where the amplitudechanges a little even if the frequency changes in order to conductmeasurements with approximately the same measurement accuracy. In thecase of FIG. 2, even if the frequency changes around about 300 Hz forthe respective powdery/granular materials, the amplitude changes alittle.

After the frequency of the vibration of the vibrator 2 is set, theevaluation value of the powdery/granular material to be measured ismeasured. The measurer first prepares for the measurement by startingthe arithmetic unit 5, the laser vibrometer 3, and electric balance 4,setting the frequency of the vibration of the vibrator 2 in thearithmetic unit 5 and throwing the powdery/granular material to bemeasured into the hopper part 111 of the tube 11 through the throw-inport 1111. Then, the measurer instructs the start of the measurement tothe arithmetic unit 5.

Upon receiving the instruction to start the measurement, the vibratorcontrolling section 511 in the central processor 51 of the arithmeticunit 5 causes the vibrator 2 to vibrate at specified frequency andamplitude only for a specified period, and the arithmetic unit 5 givesthe vibration to the tube 11 by means of the vibrator 2. The laservibrometer 3 measures the amplitude of the vibration of the tube 11 atthe specified sampling intervals, and outputs the measured amplitudes ofthe tube 11 to the arithmetic unit 5. The electric balance 4 measuresthe weight of the fallen powdery/granular material at the specifiedsampling intervals, and outputs the measured weights of thepowdery/granular material to the arithmetic unit 5. The evaluation valuecalculating section 512 in the central processor 51 of the arithmeticunit 5 stores the outputs from the laser vibrometer 3 and those from theelectric balance 4 in the storage device 52 while relating them to eachother.

Upon the lapse of a specified period, the arithmetic unit 5 causes thevibrator 2 to vibrate at the specified frequency and the next amplitudein order to conduct a measurement by causing the vibrator 2 to vibrateat the next amplitude, thereby giving vibration to the tube 11 by meansof the vibrator 2. The laser vibrometer 3 measures the amplitude of thevibration of the tube 11 at the specified sampling intervals, andoutputs the measured amplitudes of the tube 11 to the arithmetic unit 5.The electric balance 4 measures the weight of the fallenpowdery/granular material at the specified sampling intervals, andoutputs the measured weights of the powdery/granular material to thearithmetic unit 5. The evaluation value calculating section 512 in thecentral processor 51 of the arithmetic unit 5 stores the outputs fromthe laser vibrometer 3 and those from the electric balance 4 in thestorage device 52 while relating them to each other.

Thereafter, the arithmetic unit 5 similarly obtains the outputs from thelaser vibrometer 3 and those from the electric balance 4 and stores themin correspondence in the storage device 52 while successively increasingthe amplitude of the vibration generated by the vibrator 2 at specifiedintervals within a specified range.

Upon completing the measurements of the amplitudes of the tube 11corresponding to the respective amplitudes of the vibration generated bythe vibrator 2 in the specified range and the weights of the fallenpowdery/granular material, the evaluation value calculating section 512in the central processor 51 of the arithmetic unit 5 generates a graphof a flow rate per unit time in relation to amplitude based on theoutputs from the laser vibrometer 3 and those from the electric balancestored in the storage device 52, and outputs the generated graph to theoutput device 55. Since the amplitudes and weights are measured at thespecified sampling intervals, the flow rate per unit time can becalculated by dividing a difference between the present weight and theprevious weight by the time of the sampling interval. Particularly, ifthe sampling interval is set at 1 sec., the flow rate per second can becalculated by subtracting the previous weight from the present weight.Since the division processing can be omitted, a calculation time can beshortened.

The arithmetic unit 5 calculates a specified evaluation value based onthe outputs from the laser vibrometer 3 and those from the electricbalance 4 stored in the storage device 52, and outputs the calculatedevaluation value to the output device 55. For example, the evaluationvalue is a flow rate per unit time of the powdery/granular materialflowing in the tube 11 when the vibration is given to the tube 11 by thevibrator 2 so that the amplitude of the tube 11 (amplitude of thenarrower tube portion 1122 in the vicinity of the flow-out port 1123 inthis embodiment) has a specified level. The flow rates of the respectivepowdery/granular materials to be measured can be relatively evaluated bythese evaluation values. The level of the amplitude is suitably setbeforehand according to the powdery/granular material to be measured.For example, the evaluation value is the level of the amplitude of thetube 11 (amplitude of the narrower tube portion 1122 in the vicinity ofthe flow-out port 1123 in this embodiment) when the powdery/granularmaterial fell from the tube 11. A timing at which the powdery/granularmaterial fell from the tube 11 can be detected as a timing at which theelectric balance 4 detected the weight. By these evaluation values, flowstarting points of the respective powdery/granular materials to bemeasured can be relatively evaluated.

As an example, flow rates per unit time in relation to amplitude weremeasured using the tube 11 of the above respective dimensions for apolymethylmetacrylate powdery/granular material surface-treated withtitanium oxide (hereinafter, abbreviated as “PMMA-TiO₂”), apolymethylmetacrylate powdery/granular material surface-treated withaluminum oxide (hereinafter, abbreviated as “PMMA-Al₂O₃”) and apolymethylmetacrylate powdery/granular material surface-treated withsilicon oxide (hereinafter, abbreviated as “PMMA-SiO₂”), each materialhaving a particle diameter of about 10 μm. The amplitude of the narrowertube portion 1122 in the vicinity of the flow-out port 1123 was measuredas the amplitude of the tube 11. Further, the frequency characteristicsof the tube 11 were measured for the respective materials and thefrequency of the vibration of the vibrator 2 was set at 400 Hz.

PMMA-TiO₂ is formed by fusing (mechanofusing) titanium oxide particlesto the outer surfaces of polymethylmetacrylate particles. PMMA-Al₂O₃ isformed by fusing aluminum oxide particles to the outer surfaces ofpolymethylmetacrylate particles. PMMA-SiO₂ is formed by fusingpolymethylmetacrylate powdery/granular material surface-treated withsilicon oxide.

FIG. 3 are graphs showing flow rates per unit time in relation toamplitude, wherein a horizontal axis represents amplitude in μm and avertical axis represent flow rate per unit time in mg/s.

FIG. 3A shows a measurement result of PMMA-TiO₂ when an amount oftitanium oxide to be fused was changed to 0, 0.5, 1, 5 and 10 wt (weight%). □ represents measurement values when the amount of titanium oxidewas 0 wt %. ∇ represents measurement values when the amount of titaniumoxide was 0.5 wt %. Δ represents measurement values when the amount oftitanium oxide was 1 wt %. ⋄ represents measurement values when theamount of titanium oxide was 5 wt %. ◯ represents measurement valueswhen the amount of titanium oxide was 10 wt %.

FIG. 3B shows a measurement result of PMMA-Al₂O₃ when an amount ofaluminum oxide to be fused was changed to 0, 0.5, 1, 5 and 10 wt %(weight %). □ represents measurement values when the amount of aluminumoxide was 0 wt %. ∇ represents measurement values when the amount ofaluminum oxide was 0.5 wt %. Δ represents measurement values when theamount of aluminum oxide was 1 wt %. ⋄ represents measurement valueswhen the amount of aluminum oxide was 5 wt %. ◯ represents measurementvalues when the amount of aluminum oxide was 10 wt %.

FIG. 3C shows a measurement result of PMMA-SiO₂ when an amount ofsilicon oxide to be fused was changed to 0, 0.5, 1, 2, 5 and 10 wt %(weight %). □ represents measurement values when the amount of siliconoxide was 0 wt %. ∇ represents measurement values when the amount ofsilicon oxide was 0.5 wt %. ⋄ represents measurement values when theamount of silicon oxide was 1 wt %. 0 represents measurement values whenthe amount of silicon oxide was 5 wt %. ◯ represents measurement valueswhen the amount of silicon oxide was 10 wt %.

As can be understood from FIGS. 3A to 3C, the fall (flow) of thepowdery/granular material starts at a certain level of the amplitude ofthe tube 11 and, thereafter, the flow rate per unit time in relation toamplitude roughly increases as the amplitude increases, maximizes at acertain amplitude of the tube 11 and decreases as the amplitudeincreases after the maximum flow rate is kept (saturated) or immediatelyafter reaching the maximum flow rate in any of the cases of PMMA-TiO₂,PMMA-Al₂O₃ and PMMA-SiO₂.

The compressibility of the powdery/granular material is thought toconcern the fact that the flow rate per unit time in relation toamplitude has such a profile.

FIG. 4 is a graph showing the flow rate per unit time in relation toamplitude by continuous measurements. FIG. 5 are views showing CT scanimages obtained by photographing the state of the powdery/granularmaterial in the center of the narrower tube portion. In FIG. 4, ahorizontal axis represents the amplitude in μm and a vertical axisrepresents the flow rate per unit time in mg/s. FIG. 4 shows ameasurement result obtained by a measurement method to be describedlater for measurements made while the amplitude of the vibration givento the tube 11 by the vibrator 2 were continuously changed at aspecified rate within a specified range. FIG. 5A shows a CT scan imagein the narrower tube portion 1122 in a state where the powdery/granularmaterial is not falling from the tube 11 although vibration is given tothe tube 11 at an amplitude (about 50 μm) shown by an arrow A in FIG. 4.FIG. 5B shows a CT scan image in the narrower tube portion 1122immediately after the fall (flow) of the powdery/granular material wasstarted when vibration was given to the tube 11 at an amplitude (about70 μm) shown by an arrow B in FIG. 4. FIG. 5C shows a CT scan image inthe narrower tube portion 1122 in a state where the flow rate per unittime in relation to amplitude is maximized or in a state immediatelyafter the maximized state when vibration was given to the tube 11 at anamplitude (about 100 μm) shown by an arrow C in FIG. 4. FIG. 5D shows aCT scan image in the narrower tube portion 1122 in a state where theflow rate per unit time in relation to amplitude decreases as theamplitude increase when vibration was given to the tube 11 at anamplitude (about 130 μm) shown by an arrow D in FIG. 4. In FIGS. 5A to5D, upper views are horizontal sections of the central part of thenarrower tube portion 1122 and lower views are vertical sections of thecentral part of the narrower tube portion 1122. Upon CT scanning,photographing is made with the vibration stopped when reaching therespective states. FIGS. 4 and 5 show the measurement result of SiO₂having an average particle diameter of 13.6 μm in the case of vibrationat a frequency of 330 Hz.

With the powdery/granular material to be measured thrown in through thethrow-in port 1111, there are spaces (e.g. space SP1 shown in FIG. 5A)in spots in the tube 11 with a fairly rough density distribution of thepowdery/granular material. Thus, even if it is started to give thevibration to the tube 11, the flow is hindered in spots where thepowdery/granular material is dense while this vibration energy isconsumed to reduce such spaces (spots where the density of thepowdery/granular material is rough) in size. Therefore, even if it isstarted to give the vibration to the tube 11, a state where thepowdery/granular material does not fall from the tube 11 continues for awhile. When the amplitude is further increased, such spaces are reducedin size by the vibration and the rough density distribution of thepowdery/granular material is loosened up. When such spaces reach acertain size, e.g. become a space SP2 of the size shown in FIG. 5B inthe example shown in FIG. 4, the fall (flow) of the powdery/granularmaterial starts. When the amplitude is further increased, such spacesare further reduced in size by the vibration and the rough densitydistribution of the powdery/granular material is more loosened up tomake the powdery/granular material more uniform, thereby decreasing thedense spots hindering the flow of the powdery/granular material. Thus,the flow rate per unit time of the powdery/granular material alsoincreases as the amplitude increases. Then, at a certain amplitude,particle intervals become suitable for the flow of the powdery/granularmaterial as shown in FIG. 5C to maximize the flow rate per unit time ofthe powdery/granular material. When the amplitude is further increased,the particle intervals are narrowed to increase frictional forcesbetween particles and frictional forces between the inner wall of thetube 11 and the particles. Therefore, the flow rate per unit time of thepowdery/granular material decreases as the amplitude increases.

It is inferred that the aforementioned phenomenon occurs if theamplitude of the tube 11 is increased, and that there are an effect ofimproving the flowability of the powdery/granular material andsimultaneously an effect of densely filling the powdery/granularmaterial by applying external forces against the adherence and frictionof the powdery/granular material to the powdery/granular material.

As described above, a characteristic curve of the flow rate per unittime in relation to amplitude represents flowability relating to thecompressibility of the powdery/granular material. Not only depending ona difference in the flowability of the powdery/granular material, butalso depending on a difference in the compressibility of thepowdery/granular material, the value of the amplitude at which the flowof the powdery/granular material starts, the increasing rate of the flowrate per unit time in relation to the increasing rate of the amplitude,the maximum flow rate, the level of the amplitude to give the maximumflow rate, the amplitude range to give the maximum flow rate and thedecreasing rate of the flow rate per unit time in relation to theincreasing rate of the amplitude after reaching the maximum flow rateand the like differ, wherefore the characteristic curve takes on variousshapes. The value of the amplitude at which the flow of thepowdery/granular material starts, the increasing rate of the flow rateper unit time in relation to the increasing rate of the amplitude, themaximum flow rate, the level of the amplitude to give the maximum flowrate, the amplitude range to give the maximum flow rate and thedecreasing rate of the flow rate per unit time in relation to theincreasing rate of the amplitude after reaching the maximum flow rate,which characterize these characteristic curves, can be used asevaluation values for the flowability of the powdery/granular material.

As can be understood from FIGS. 3A to 3C, the amplitude of the tube(amplitude when the flow rate per unit time=0 in FIG. 3) when thepowdery/granular material fell from the tube 11 differs depending on anamount of the surface treating material (TiO₂, Al₂O₃ and SiO₂) in any ofthe cases of PMMA-TiO₂, PMMA-Al₂O₃ and PMMA-SiO₂. For example, in thecase of PMMA-TiO₂ shown in FIG. 3A, the amplitude of the tube 11 whenthe powdery/granular material fell from the tube 11 was about 47 μm whenthe content of titanium oxide was 0 wt %, about 30 μm when the contentof titanium oxide was 0.5 wt %, about 17 μm when the content of titaniumoxide was 1 wt %, about 12 μm when the content of titanium oxide was 5wt % and about 9 μm when the content of titanium oxide was 10 wt %. As aresult, PMMA-TiO₂ can be understood to increase its flowability as theamount of TiO₂ fused to the outer surfaces increases. In this way, theamplitude of the tube 11 when the powdery/granular material fell fromthe tube 11 can be used as the evaluation value for the flowability ofthe powdery/granular material. Of course, this evaluation value for theflowability is also a value relating to the compressibility of thepowdery/granular material as described above and can be used as anevaluation value for the compressibility if the compressibility of thepowdery/granular material is a main viewpoint.

As can be further understood from FIGS. 3A to 3C, the flow rate per unittime of the powdery/granular material flowing in the tube 11 in the casewhere vibration is given to the tube 11 by the vibrator 2 so that theamplitude of the tube 11 (amplitude of the narrower tube portion 1122 inthe vicinity of the flow-out port 1123 in this embodiment) has aspecified level differs depending on an amount of the surface treatingmaterial (TiO₂, Al₂O₃ and SiO₂) in any of the cases of PMMA-TiO₂,PMMA-Al₂O₃ and PMMA-SiO₂. For example, in the case of PMMA-TiO₂ shown inFIG. 3A and the amplitude of the tube 11 of 40 μm, the flow rate perunit time of the powdery/granular material was about 0 mg/s when thecontent of titanium oxide is 0 wt %, about 2 mg/s when the content oftitanium oxide was 0.5 wt %, about 9 mg/s when the content of titaniumoxide was 1 wt %, about 11.2 mg/s when the content of titanium oxide was5 wt % and about 15 mg/s when the content of titanium oxide was 10 wt %.As a result, PMMA-TiO₂ can be understood to increase its flowability asthe amount of TiO₂ fused to the outer surfaces increases. In this way,the flow rate per unit time of the powdery/granular material flowing inthe tube 11 in the case where vibration is given to the tube 11 by thevibrator 2 so that the amplitude of the tube 11 has a specified levelcan be used as the evaluation value for the flowability of thepowdery/granular material. Of course, this evaluation value for theflowability is also a value relating to the compressibility of thepowdery/granular material as described above and can be used as anevaluation value for the compressibility if the compressibility of thepowdery/granular material is a main viewpoint.

Alternatively, a change of the flow rate per unit time of thepowdery/granular material flowing in the tube 11 with time in the casewhere vibration is given to the tube 11 by the vibrator 2 so that theamplitude of the tube 11 (amplitude of the narrower tube portion 1122 inthe vicinity of the flow-out port 1123 in this embodiment) has aspecified level may be used as the evaluation value for the flowabilityof the powdery/granular material.

FIG. 6 are graphs showing changes in the flowing rate per unit time ofthe powdery/granular material with time at specified amplitudes. In FIG.6, a horizontal axis represents the elapsed time in seconds and avertical axis represents the flow rate per unit time in mg/s. FIG. 6show measurement results of PMMA having an average particle diameter ofabout 58.2 μm in the case of vibration at a frequency of 330 Hz. FIG. 6Ashows a case where the amplitude was about 12.4 μm, FIG. 6B shows a casewhere the amplitude was 28.7 μm and FIG. 6C shows a case where theamplitude was 52.8 μm.

The changes of the flow rate per unit time of the powdery/granularmaterial with time at the specified amplitudes are categorized intocases where the flow rate per unit time of the powdery/granular materialrepeatedly changes in its magnitude to pulsate as time elapses (pulsatedflow) as shown in FIGS. 6A and 6B, cases where the flow rate per unittime of the powdery/granular material is substantially constant withouthardly changing as time elapses (constant flow) as shown in FIG. 6C andunillustrated cases where the flow temporarily stops to create the flowlike pulses and the powdery/granular material intermittently flows(intermittent flow). The changes of the flow rate per unit time of thepowdery/granular material with time at the specified amplitudes dependon the level of the amplitude of the vibration because the flow changesfrom the pulsated flow to the constant flow as the amplitude increasesin the example shown in FIG. 6. Further, even in the pulsated flows, asthe amplitude increases, changes in the flow rate per unit time changefrom a state where amplitudes are smaller to a state where amplitudesare larger and from a state where the frequency is high to a state wherethe frequency is low.

As described above, the change of the flow rate per unit time of thepowdery/granular material flowing in the tube 11 with time in the casewhere vibration is given to the tube 11 by the vibrator 2 so that theamplitude of the tube 11 has a specified level can be used as theevaluation value for the flowability of the powdery/granular materialand, particularly, the stability of the flow can be evaluated dependingon the presence or absence of the pulsation, i.e. whether the flow is apulsated flow or an intermittent flow, or a constant flow.

Although the powdery/granular material flowability evaluation apparatusA is constructed to generate and output the graph of the flow rate perunit time in relation to amplitude in the above embodiment, it may beconstructed to measure only the amplitude of the tube 11 when thepowdery/granular material fell from the tube 11, calculate and outputthe evaluation value. Alternatively, the powdery/granular materialflowability evaluation apparatus A may be constructed to give vibrationto the tube 11 by means of the vibrator 2 so that the amplitude of thetube 11 has a specified level, measure only the flow rate per unit timeof the powdery/granular material flowing in the tube 11 in this case,calculate and output the evaluation value.

Further, in the above embodiment, the powdery/granular materialflowability evaluation apparatus A is constructed to measure theamplitude of the tube and the weight of the fallen powdery/granularmaterial at each one of the amplitudes of the vibration of the vibrator2 within the specified range by giving the vibration of a certainamplitude to the tube 11 by means of the vibrator 2 only for a specifiedtime and successively increasing this amplitude at specified intervalsof time. However, the powdery/granular material flowability evaluationapparatus A may be constructed to measure the amplitude of the tube andthe weight of the fallen powdery/granular material while the amplitudeof the vibration given to the tube 11 by means of the vibrator 2 iscontinuously changed at a specified rate within the specified range. Bythis construction, the graph of the flow rate per unit time in relationto amplitude can be obtained and the specified evaluation value can becalculated within a shorter period of time. A rate at which theamplitude of the vibration is continuously changed can be suitably setaccording to the powdery/granular material to be measured.

Alternatively, the powdery/granular material flowability evaluationapparatus A may be constructed as follows in the case where theamplitude of the vibration given to the tube 11 by means of the vibrator2 is continuously changed at the specified rate within the specifiedrange. A relationship between the amplitude continuously changing at thespecified rate and the elapsed time (elapsed time-amplituderelationship) is obtained beforehand. Instead of measuring the amplitudeof the tube 11, an elapsed time-amplitude relationship informationstorage 521 storing information representing the thus obtained elapsedtime-amplitude relationship (elapsed time-amplitude relationshipinformation) is functionally provided in the storage device 52 as shownin broken line in FIG. 1, and the evaluation value calculating section512 calculates the evaluation value evaluating the flowability of thepowdery/granular material based on the elapsed time-amplituderelationship stored in the elapsed time-amplitude relationshipinformation storage 521 beforehand and the weight measured by theelectric balance 4.

The elapsed time-amplitude relationship is, for example, represented byan arithmetic expression defining a relationship between the elapsedtime and the amplitude or a lookup table defining a correspondencebetween the elapsed time and the amplitude. Further, the evaluationvalue calculating section 512 calculates the evaluation value of thepowdery/granular material, for example, by converting the elapsed timefrom the start of the measurement to a timing of notification into anamplitude using the elapsed time-amplitude relationship upon receivingthe notification of the weight of the powdery/granular material from theelectric balance 4 via the interface 53 and obtaining a graph of theflow rate per unit time in relation to amplitude from the weight of thepowdery/granular material notified from the electric balance 4 and theconverted amplitude.

By this construction as well, the graph of the flow rate per unit timein relation to amplitude can be obtained and the specified evaluationvalue can be calculated within a shorter period of time.

FIG. 7 is a graph showing a flow rate per unit time in relation toelapsed time. In FIG. 7, a horizontal axis represents time in secondsand a vertical axis represents flow rate in mg/s. Although thehorizontal axis represents time in FIG. 7, it also represents amplitudesince the amplitude is continuously changed at a specified rate. FIG. 7shows a measurement result in the case the vibrator 2 is controlled toincrease the amplitude of the vibration given to the tube 11 from 0 to130 μm for two minutes for a copper (Cu) powdery/granular materialhaving an average particle diameter of about 5 μm and an aluminum oxide(Al₂O₃) powdery/granular material having an average particle diameter ofabout 10.5 μm, i.e. a measurement result in the case where the amplitudeis continuously increased at a rate of 130/120 μm/s. The frequency ofthe vibration is 330 Hz. ⋄ represents the measurement result of copperand ▴ represents the measurement result of aluminum oxide.

In the example shown in FIG. 7, the evaluation value for copper is about22.7 μm (=130/120×21) and the one for aluminum oxide is about 32.5 μm(=130/120×30) as can be understood from FIG. 7 if the amplitude of thetube 11 when the powdery/granular material fell from the tube 11 isassumed as the evaluation value for the flowability. If the flow rateper unit time of the powdery/granular material flowing in the tube 11 inthe case where the vibration is given to the tube 11 by the vibrator 2so that the amplitude of the tube 11 has a specified level is assumed asthe evaluation value for the flowability, the evaluation value forcopper is about 55 mg/s and the evaluation value for aluminum oxide isabout 23 mg/s, for example, when the elapse time is 60 sec. (i.e.amplitude is 65 μm). As a result, it can be understood that the copperhas higher flowability than aluminum oxide.

FIG. 8 is a graph showing cumulative amounts of powdery/granularmaterials flown out from the tube in relation to an amplitude changeaccording to another example. In FIG. 8, a horizontal axis representsamplitude in μm and a vertical axis represent cumulative amount of thepowdery/granular material flown out from the tube 11 in g. Although thehorizontal axis represents amplitude in μm in FIG. 8, it also representselapsed time since the amplitude is continuously changed at a specifiedrate. Further, in FIG. 8, the flow rates per unit time can be obtainedas in FIG. 7 by time-differentiating the cumulative amounts of thepowdery/granular materials flown out from the tube 11. FIG. 8 showsmeasurement results in the case of controlling the vibrator 2 toincrease the amplitude of the vibration given to the tube 11 from 0 to130 μm for two minutes for the respective PMMA powdery/granularmaterials having an average particle diameter of about 5.2 μm (□), about6.7 μm (⋄), about 12.3 μm (Δ), about 13.8 μm (◯), about 17.3 μm (*),about 27.6 μm (▪), about 38.9 μm (♦), about 47.9 μm (▴) and about 58.2μm (). The frequency of the vibration is 330 Hz.

In the example shown in FIG. 8, the evaluation value is smaller as theaverage particle increases and the fall of the powdery/granular materialstarts at a smaller amplitude if the amplitude of the tube 11 when thepowdery/granular material first fell from the tube 11 is assumed as theevaluation value for the flowability as can be understood from FIG. 8.Further, if the flow rate per unit time of the powdery/granular materialflowing in the tube 11 in the case where the vibration is given to thetube 11 by the vibrator 2 so that the amplitude of the tube has aspecified level is assumed as the evaluation value for the flowability,it can be understood from the inclinations of the respectivecharacteristic curves shown in FIG. 8 that the evaluation value islarger and the flowability is higher as the average particle diameterincreases.

Although the measurements were made by giving the vibration to the tube11 while the amplitude was continuously changed at the specified rate inFIGS. 4, 7 and 8, they may be made by giving the vibration to the tube11 while the amplitude is continuously decreased at a specified rate.

In the above embodiment, the powdery/granular material flowabilityevaluation apparatus A is constructed to measure the amplitude of thetube 11 and the weight of the fallen powdery/granular material at eachone of the amplitudes of the vibration of the vibrator 2 within thespecified range by giving the vibration of a certain amplitude to thetube 11 by means of the vibrator 2 only for the specified time andsuccessively increasing this amplitude at the specified intervals oftime. However, the powdery/granular material flowability evaluationapparatus A may be constructed to measure the amplitude of the tube 11and the weight of the fallen powdery/granular material while theamplitude of the vibration given to the tube 11 by means of the vibrator2 is continuously decreased or increased at a specified rate after beingcontinuously increased or decreased at a specified rate up to a presetlevel. By this construction, the graph of the flow rate per unit time inrelation to amplitude can be obtained within a shorter period of timeand a hysteresis of the flow rate per unit time in relation to amplitudecan be obtained.

Alternatively, the powdery/granular material flowability evaluationapparatus A may be constructed as follows in the case where theamplitude of the vibration given to the tube 11 by means of the vibrator2 within the specified range is continuously decreased or increased atthe specified rate after being continuously increased or decreased atthe specified rate up to the preset level. A relationship between theamplitude continuously changing at the specified rate and an elapsedtime (elapsed time-amplitude relationship) is obtained beforehand.Instead of measuring the amplitude of the tube 11, an elapsedtime-amplitude relationship information storage 521 (shown in brokenline in FIG. 1) storing information representing the elapsedtime-amplitude relationship (elapsed time-amplitude relationshipinformation) thus obtained beforehand as described above is functionallyprovided in the storage device 52, and the evaluation value calculatingsection 512 calculates the evaluation value evaluating the flowabilityof the powdery/granular material based on the elapsed time-amplituderelationship stored in the elapsed time-amplitude relationshipinformation storage 521 beforehand and the weight measured by theelectric balance 4.

By this construction as well, the graph of the flow rate per unit timein relation to amplitude can be obtained within a shorter period of timeand a hysteresis of the flow rate per unit time in relation to amplitudecan be obtained.

FIG. 9 is a graph showing cumulative amounts of powdery/granularmaterials flown out from the tube in relation to an amplitude change inthe case where the amplitude of the vibration is decreased after beingincreased to a specified level. In FIG. 9, a horizontal axis representsthe amplitude in μm and a vertical axis represents the cumulative amountof the powdery/granular material flown out from the tube 11 in g.Although the horizontal axis represents the amplitude in FIG. 9, it alsorepresents an elapsed time since the amplitude is continuously changedat a specified rate. In FIG. 9, the flow rates per unit time can beobtained as in FIG. 7 by time-differentiating the cumulative amounts ofthe powdery/granular materials flown out from the tube 11. FIG. 9 showsmeasurement results in the case of controlling the vibrator 2 todecrease the amplitude of the vibration given to the tube 11 for PMMApowdery/granular materials having an average particle diameter of about58.2 μm from 130 to 0 μm for two minutes after increasing this amplitudefrom 0 to 130 μm for two minutes. The frequency of the vibrator is 330Hz. In the example shown in FIG. 9, three measurements are conducted,wherein the first one (Test 1) is shown by □, the second one (Test 2) byΔ and the third one (Test 3) by ◯ and an average of these is shown by .

As can be understood from FIG. 9, if the amplitude of the vibrationgiven to the tube 11 by the vibrator 2 is continuously decreased at thespecified rate after being continuously increased at the specified rateup to the specified level, the change of the cumulative amount of thepowdery/granular material flown out from the tube in relation to theamplitude change, i.e. the change of the flow rate per unit time inrelation to the amplitude change, differs between the case where theamplitude of the vibration is continuously increased at the specifiedrate up to the specified level and the case where the amplitude of thevibration is thereafter continuously decreased at the specified rate upto the specified level. Specifically, if the amplitude of the vibrationgiven to the tube 11 by the vibrator 2 is continuously decreased at thespecified rate after being continuously increased at the specified rateup to the specified level, the change of the cumulative amount of thepowdery/granular material flown out from the tube in relation to theamplitude change (change of the flow rate per unit time in relation tothe amplitude change) draws a hysteresis curve. In the example shown inFIG. 9, the change of the cumulative amount of the powdery/granularmaterial flown out from the tube in relation to the amplitude change(change of the flow rate per unit time in relation to the amplitudechange) takes on different profiles particularly in the case where theamplitude is increased from 0 to about 60 μm and in the case where theamplitude is decreased from about 60 to 0 μm.

This is because the vibration energy is first consumed to reduce thespaces formed in spots (parts where the density of the powdery/granularmaterial is rough) and the flow of the powdery/granular material startsat a certain amplitude as described above in the case of increasing theamplitude from 0 to 130 μm, but such spaces are already reduced in sizeand there are hardly no spots hindering the flow of the powdery/granularmaterial in the case of decreasing the amplitude from 130 to 0 μm. Thus,the powdery/granular material does not flow in the case of increasingthe amplitude in a range from 0 to 20 μm, whereas the flow can be seenin the case of decreasing the amplitude in a range from 20 to 0 μm.

Such a hysteresis of the change of the flow rate per unit time inrelation to the amplitude change can be used as the evaluation value forthe flowability of the powdery/granular material and particularly as theevaluation value for the flowability also considering thecompressibility of the powdery/granular material.

Although the vibrator 2 includes one vibrator main body 21 forgenerating vibration and gives vibration to the tube 11 in one directionin a horizontal plane with respect to the longitudinal direction of thetube 11 in the above embodiment, it may include a plurality of vibratormain bodies for generating vibrations and may give vibrations to thetube 11 in different directions in a horizontal plane with respect tothe longitudinal direction of the tube 11. In this case, the vibrator 2includes, for example, a vibrator main body (first vibrator main body)21 and a second vibrator main body 23 shown in broken line in FIG. 1 forgenerating the vibrations, and a vibration transmitting member 22 fortransmitting the vibrations generated by the first and second vibratormain bodies 21, 23.

FIG. 10 is a horizontal section along X-X of FIG. 1 showing a statewhere the first and second vibrator main bodies 21, 23 are attached tothe tube 11 via the vibration transmitting member 22. As shown in FIGS.1 and 10, the first and second vibrator main bodies 21, 23 are soattached to the tube 11 via the vibration transmitting member 22 so thatthe vibrations are given to the tube 11 in mutually different directionsin a horizontal plane with respect to the longitudinal direction of thetube 11. In the example shown in FIGS. 1 and 10, the first and secondvibrator main bodies 21, 23 are attached to the tube 11 via thevibration transmitting member 22 so as to give the vibrations to thetube 11 in orthogonal directions.

The first and second vibrator main bodies 21, 23 give the vibrations tothe tube 11 via the vibration transmitting member 22 at specifiedfrequency and amplitude in accordance with a control signal from thearithmetic unit 5. The vibrations given to the tube 11 by the first andsecond vibrator main bodies 21, 23 may have mutually differentwaveforms.

FIG. 11 is a graph showing a flow rate per unit time in relation to anelapsed time in the case where vibrations having different waveforms aregiven to the tube in two directions. In FIG. 11, a horizontal axisrepresents time in seconds and a vertical axis represents a flow rate ing/s. Although the horizontal axis represents the time in FIG. 11, italso represents the amplitude since the amplitude is continuouslychanged at a specified rate. FIG. 11 shows measurement results forspherical silica having an average particle diameter of about 20 μm. Thefirst vibrator main body 21 gave vibration to the tube 11 to increasethe amplitude from 0 to 130 μm for two minutes at a frequency of 330 Hzin any one of the following cases. ▪ represents a measurement result inthe case where the second vibrator main body 23 gave rectangular wavevibration having an amplitude of 50 μm to the tube 11 at a frequency of2 Hz. A represents a measurement result in the case where the secondvibrator main body 23 gave pulsed vibration having an amplitude of 50 μmto the tube 11 at a frequency of 2 Hz. Further, ⋄ represents ameasurement result as a reference data in the case where the secondvibrator main body 23 gave no vibration to the tube 11.

As can be understood from FIG. 11, if the vibration having a lowerfrequency than that of the first vibrator main body 21 is given to thetube 11 by the second vibrator main body 23, the value of the amplitudeat which the flow of the powdery/granular material starts (flow startingpoint) in the characteristic curve of the flow rate per unit time inrelation to amplitude does not change, but the succeeding flow rate inthis characteristic curve is larger as compared to the case where novibration is given to the tube 11 by the second vibrator main body 23.Thus, in the powdery/granular material flowability evaluation apparatusA having such a construction, hindrance to the flow caused by cross-linkformation can be suppressed and such evaluation values among therespective powdery/granular materials to be measured can be obtainedwithin a short period of time.

Although the frequency is relatively low in the above example, a higherfrequency or a frequency in the ultrasonic range may be, of course,selected as already described that an ultrasonic vibrator apparatus canbe adopted as the vibrator 2.

Although the vibration of the tube 11 is measured by the laservibrometer 3 in the above embodiment, it may be obtained based on thelevel of the drive voltage for driving the vibrator main body 21 (23) ofthe vibrator 2 since the amplitude of the vibrator in the vibrator mainbody 21 (23) of the vibrator 2 is proportional to the level (magnitude)of the drive voltage for driving the vibrator main body 21 (23). Forexample, a relationship between the level of the drive voltage and theamplitude of the tube 11 is obtained beforehand, and the amplitude ofthe tube 11 is obtained from the level of the drive voltage using thisrelationship. By constructing the powdery/granular material flowabilityevaluation apparatus A in this way, the amplitude can be measured evenif the tube 11 vibrates in the high-frequency range or ultrasonic range.

Alternatively, the powdery/granular material flowability evaluationapparatus A may be constructed such that a piezoelectric element bondedover the entire circumference to the outer circumferential surface ofthe narrower tube portion 1122 in the vicinity of the flow-out port 1123of the tube 11 may be used instead of the laser vibrometer 3 to measurethe amplitude of the tube 11. The piezoelectric element bonded to thenarrower tube portion 1122 is distorted by the vibration of the narrowertube portion 1122 and outputs a voltage corresponding to thisdistortion. By constructing the powdery/granular material flowabilityevaluation apparatus A in this way, the amplitude can be measured evenif the tube 11 vibrates in the high-frequency range or ultrasonic range.

In this specification are disclosed various inventions as above, out ofwhich main inventions are summarized below.

A powdery/granular material flowability evaluation apparatus accordingto one aspect of the present invention comprises a storage tank forstoring a powdery/granular material to be evaluated; a vertical orinclined tube whose flow-out port is connected with a discharge port ofthe storage tank through which the powdery/granular material isdischarged; a vibrator unit for giving vibration to the tube; anamplitude meter for measuring the amplitude of the tube; a weight meterfor measuring the weight of the powdery/granular material fallen throughthe tube from the storage tank; and an evaluation value calculator forcalculating an evaluation value evaluating the flowability of thepowdery/granular material based on the amplitude measured by theamplitude meter and the weight measured by the weight meter. Apowdery/granular material flowability evaluation method according toanother aspect of the present invention comprises the steps of givingvibration to a vertical or inclined tube having a storage tank forstoring a powdery/granular material to be measured arranged at one endthereof such that the powdery/granular material flows into the tube fromthe storage tank; measuring the amplitude of the tube; measuring theweight of the powdery/granular material fallen through the tube from thestorage tank; and calculating an evaluation value evaluating theflowability of the powdery/granular material based on the measuredamplitude and weight.

According to the above powdery/granular material flowability evaluationapparatus and powdery/granular material flowability evaluation method,the flowability of the powdery/granular material can be evaluated in adynamic state where the powdery/granular material itself is flowing oris about to start flowing.

In the above powdery/granular material flowability evaluation apparatus,the vibrator unit gives the vibration to the tube while continuouslychanging the amplitude of the vibration at a specified rate. Further, inthe above powdery/granular material flowability evaluation apparatus,the vibrator unit gives the vibration to the tube while continuouslychanging the amplitude of the vibration at a specified rate; a storagedevice storing a relationship between the amplitude continuouslychanging at the specified rate and an elapsed time beforehand isprovided instead of the amplitude meter; and the evaluation valuecalculator calculates the evaluation value evaluating the flowability ofthe powdery/granular material based on the relationship stored in thestorage device and the weight measured by the weight meter. In thepowdery/granular material flowability evaluation apparatus having such aconstruction, a specified evaluation value can be calculated within ashorter period of time.

Further, in the above powdery/granular material flowability evaluationapparatus, a continuous change given by the vibrator unit is a change ofdecreasing or increasing the amplitude after increasing or decreasingthe amplitude up to a specified level. In the powdery/granular materialflowability evaluation apparatus having such a construction, a specifiedevaluation value can be calculated within a shorter period of time.Particularly, a hysteresis of a change of a flow rate per unit time inrelation to an amplitude change can be calculated as an evaluation valuefor the flowability. By dosing so, hystereses of the flows amongpowdery/granular materials to be measured can be relatively evaluated.

In these above powdery/granular material flowability evaluationapparatuses, the evaluation value is a flow rate per unit time of thepowdery/granular material flowing in the tube in the case wherevibration is given to the tube by the vibrator unit so that theamplitude of the tube has a specified level. In the powdery/granularmaterial flowability evaluation apparatuses having such a construction,the flow rates of the powdery/granular materials to be measured can berelatively evaluated by such evaluation values.

Further, in these above powdery/granular material flowability evaluationapparatuses, the evaluation value is a change of the flow rate per unittime of the powdery/granular material flowing in the tube with time inthe tube in the case where vibration is given to the tube by thevibrator unit so that the amplitude of the tube has a specified level.In the powdery/granular material flowability evaluation apparatuseshaving such a construction, stabilities and compressibilities, andflowabilities of the powdery/granular materials to be measured can berelatively evaluated by such evaluation values.

Furthermore, in these above powdery/granular material flowabilityevaluation apparatuses, the evaluation value is the amplitude of thetube when the powdery/granular material first fell from the tube. In thepowdery/granular material flowability evaluation apparatuses having sucha construction, the flow starting points of the powdery/granularmaterials to be measured can be relatively evaluated by such evaluationvalues.

Further, in these above powdery/granular material flowability evaluationapparatuses, the vibrator unit gives vibrations to the tube in mutuallydifferent directions in a horizontal plane with respect to thelongitudinal direction of the tube. Furthermore, in these abovepowdery/granular material flowability evaluation apparatuses, therespective vibrations given to the tube in the mutually differentdirections in the horizontal plane with respect to the longitudinaldirection of the tube have waveforms different from each other. In thepowdery/granular material flowability evaluation apparatuses having sucha construction, hindrance to the flow by cross-link formation can besuppressed. Therefore, the value of the amplitude at which thepowdery/granular material starts flowing and a maximum flow rate in acharacteristic curve of the flow rate per unit time in relation toamplitude can be measured within a shorter period of time.

Further, in these above powdery/granular material flowability evaluationapparatuses, the vibrator unit includes a piezoelectric element. In thepowdery/granular material flowability evaluation apparatuses having sucha construction, the amplitude of the vibration can be easilycontinuously changed while the frequency is fixed at a specifiedfrequency set beforehand since the amplitude and frequency (number ofvibration) of the vibration can be independently controlled.

Although the present invention has been suitably and adequatelydescribed above by way of the embodiment while referring to the drawingsin order to represent the present invention, it should be appreciatedthat a person skilled in the art can easily modify and/or improve theabove embodiment. Accordingly, unless modified or improved embodiment ofthe person skilled in the art departs from the scope of the right asclaimed, such modified or improved embodiment should be understood to beembraced by the scope as claimed.

INDUSTRIAL APPLICABILITY

According to the present invention, there can be provided apowdery/granular material flowability evaluation apparatus and apowdery/granular material flowability evaluation method capable ofrelatively evaluating the flowability of a powdery/granular material.

1. A powdery/granular material flowability evaluation apparatus,characterized by giving vibration to an accommodating memberaccommodating a powdery/granular material and calculating an evaluationvalue evaluating the flowability of the powdery/granular material basedon the amplitude of the given vibration and the weight of thepowdery/granular material having come out of the accommodating member bythe given vibration.